Laptop partial power. Please help.

My mate has given me his laptop to look at as it is not working.

It is a powerful and modified Dell XPS M1730 with SLI and goodness knows what.
It recently started freezing on him (which meant the only way to shutdown was to pull the plug) but upon booting up again everything was fine. I thought this sounded like an overheating issue.

Anyway, now when the power button is pressed, the hard drive spins up (I can hear it), there is power to the DVD drive, LED's iluminate etc.....
....but NO fans are spinning (I have looked through the grills on the bottom through which I can see at least 3 fans.
The screen remains blank and the machine does not boot up.

Please can I have suggestions as to what could be the cause and what I could check.

I am comfortable with technical talk and have all the tools necessary to carry out surgery!

Many thanks all.

http://support.dell.com/support/topics/global.aspx/s...

What sort of diagnostic light sequence do you see.

Thank you for that (I never knew that page existed) only no lights illuminate at all bar the Power, Hard Drive and Bluetooth LED's